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https://github.com/Z3Prover/z3
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71 lines
2.4 KiB
C++
71 lines
2.4 KiB
C++
/*++
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Copyright (c) 2021 Microsoft Corporation
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Module Name:
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polysat clause builder
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Author:
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Jakob Rath 2021-04-6
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Notes:
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Builds a clause from literals and constraints.
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Skips trivial new constraints such as "4 <= 1".
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--*/
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#pragma once
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#include "math/polysat/clause.h"
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#include "math/polysat/constraint.h"
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#include "math/polysat/types.h"
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namespace polysat {
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class clause_builder {
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solver* m_solver;
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sat::literal_vector m_literals;
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/// True iff clause contains a literal that is always true
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/// (only this specific case of tautology is covered by this flag)
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bool m_is_tautology = false;
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bool m_redundant = clause::redundant_default;
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public:
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clause_builder(solver& s);
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clause_builder(clause_builder const& s) = delete;
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clause_builder(clause_builder&& s) = default;
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clause_builder& operator=(clause_builder const& s) = delete;
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clause_builder& operator=(clause_builder&& s) = default;
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bool empty() const { return m_literals.empty() && !m_is_tautology && m_redundant == clause::redundant_default; }
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void reset();
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void set_redundant(bool r) { m_redundant = r; }
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/// Build the clause. This will reset the clause builder so it can be reused.
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/// Returns nullptr if the clause is a tautology and should not be added to the solver.
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clause_ref build();
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/// Insert constraints into the clause.
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void insert(sat::literal lit);
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void insert(signed_constraint c);
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/// Insert constraints into the clause.
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/// If they are not yet on the search stack, add them as evaluated to \b false.
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/// \pre Constraint must be \b false in the current assignment.
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void insert_eval(sat::literal lit);
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void insert_eval(signed_constraint c);
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/// Insert constraints into the clause.
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/// If possible, evaluate them as in insert_eval.
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/// Evaluation might not be possible if not all variables in the constraint are assigned.
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/// \pre Constraint must be \b non-true in the current assignment.
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void insert_try_eval(sat::literal lit);
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void insert_try_eval(signed_constraint lit);
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using const_iterator = decltype(m_literals)::const_iterator;
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const_iterator begin() const { return m_literals.begin(); }
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const_iterator end() const { return m_literals.end(); }
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};
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}
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